A \(220\) V input is supplied to a transformer. The output circuit draws a current of \(2.0\) A at \(440\) V. What is the current drawn by the primary windings of the transformer if the efficiency of the transformer is \(80\%\)?
1. \(3.6\) A
2. \(2.8\) A
3. \(2.5\) A
4. \(5.0\) A

Subtopic:  Transformer |
 77%
Level 2: 60%+
AIPMT - 2010
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An alternating voltage source is connected to a series \(RC\) circuit. Consider two situations:
1. When the capacitor is air-filled. 
2. When the capacitor is mica filled. 

If the current through the resistor is \(I\) and the voltage across the capacitor is \(V\), then:
1. \(V_a < V_b\)
2. \(V_a > V_b\)
3. \(i_a > i_b\)
4. \(V_a = V_b\)

Subtopic:  Different Types of AC Circuits |
 66%
Level 2: 60%+
NEET - 2015
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A resistance \(R\) draws power \(P\) when connected to an AC source. If an inductance is now placed in series with the resistance, such that the impedance of the circuit becomes \(Z\) the power drawn will be:
\(1 .\) \(P \left(\frac{R}{Z}\right)^{2}\)
\(2 .\) \(P \sqrt{\frac{R}{Z}}\)
\(3 .\) \(P \left(\frac{R}{Z}\right)\)
\(4 .\) \(P\)
Subtopic:  Power factor |
 60%
Level 2: 60%+
NEET - 2015
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The diagram shows a capacitor \(C\) and a resistor \(R\) connected in series to an AC source. \(V_1\) and \(V_2\) are voltmeters and \(A\) is an ammeter.

              

Consider now the following statements
I. Readings in \(A\) and \(V_2\) are always in phase
II. Reading in \(V_1\) is ahead in phase with reading in \(V_2\)
III. Readings in \(A\) and \(V_1\) are always in phase
Which of these statements is/are correct?
1. I only 2. II only
3. I and II only 4. II and III only
Subtopic:  Different Types of AC Circuits |
 64%
Level 2: 60%+
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The figure shows the variation of \(R\), \(X_L\), and \(X_C\) with frequency \(f\) in a series of \(L\), \(C\), and \(R\) circuits. For which frequency point is the circuit inductive?

          

1. \(A\) 2. \(B\)
3. \(C\) 4. All points
Subtopic:  Different Types of AC Circuits |
 57%
Level 3: 35%-60%
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One \(10~\text{V}\), \(60~\text{W}\) bulb is to be connected to \(100~\text{V}\) line. The required induction coil has a self-inductance of value:
(\(f= 50~\text{Hz}\)) 
1. \(0.052\) H 2. \(2.42\) H
3. \(16.2\) mH 4. \(1.62\) mH
Subtopic:  Different Types of AC Circuits |
 56%
Level 3: 35%-60%
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In an \(LCR\) series network, \(V_L = 40~\text{V}, V_C = 20~\text{V}~\text{and}~V_R = 15~\text{V}.\) The supply voltage will be:
1. \(25~\text{V}\)
2. \(75~\text{V}\)
3. \(35~\text{V}\)
4. zero

Subtopic:  Different Types of AC Circuits |
 89%
Level 1: 80%+
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An alternating current is given as \(i = i_1\cos\omega t- i_2 \sin \omega t.\) The value of rms current is given by:
1. \( \frac{1}{\sqrt{2}}\left(i_1+i_2\right) \)
2. \( \frac{1}{\sqrt{2}}\left(i_i+i_2\right)^2 \)
3. \( \frac{1}{\sqrt{2}}\left(i_1^2+i_2^2\right)^{1 / 2} \)
4. \( \frac{1}{2}\left(i_1^2+i_2^2\right)^{1 / 2}\)
Subtopic:  RMS & Average Values |
 81%
Level 1: 80%+
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In a step-up transformer, the turn ratio is \(1:2\). A Leclanche cell (emf \(1.5\) V) is connected across the primary coil. What would be the voltage developed in the secondary coil?
1. \(3.0\) V 2. \(0.75\) V
3. \(1.5\) V 4. Zero
Subtopic:  Transformer |
Level 3: 35%-60%
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A \(220\) V, \(50\) Hz AC source is connected to an inductance of \(0.2\) H and a resistance of \(20\) ohms in series. How much current flows across the circuit?
1. \(10\) A
2. \(5\) A
3. \(33.3\) A
4. \(3.33\) A
Subtopic:  Different Types of AC Circuits |
 69%
Level 2: 60%+
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